Inhibitors of mammalian target of rapamycin downregulate MYCN protein expression and inhibit neuroblastoma growth in vitro and in vivo

Johnsen, John Inge; Segerström, Lova; Orrego, Abiel; Elfman, Lotta; Henriksson, Marie Arsenian; Kågedal, Bertil; Eksborg, Staffan; Sveinbjørnsson, Baldur; Kogner, Per

doi:10.1038/sj.onc.1210938

Cited by 149 publications

(167 citation statements)

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“…Previous reports have indicated that inhibition of PI3K pathway influences both MYCN expression and stability in a mouse model. 22 MYCN stability is complex and incompletely understood 17,21,22,42,43 (and references therein). Our results are in agreement with role for ALK in regulating levels of MYCN in neuroblastoma cells.…”

Section: Resultsmentioning

confidence: 99%

Anaplastic Lymphoma Kinase (ALK) regulates initiation of transcription of MYCN in neuroblastoma cells

et al. 2012

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Neuroblastoma is a neural crest-derived embryonal tumour of the postganglionic sympathetic nervous system and a disease with several different chromosomal gains and losses, which include MYCN-amplified neuroblastoma on chromosome 2, deletions of parts of the chromosomes 1p and 11q, gain of parts of 17q and triploidy. Recently, activating mutations of the ALK (Anaplastic Lymphoma Kinase) RTK (Receptor Tyrosine Kinase) gene have been described in neuroblastoma. A meta-analysis of neuroblastoma cases revealed that ALK mutations (49 of 709 cases) in relation to genomic subtype were most frequently observed in MYCN amplified tumours (8.9%), correlating with a poor clinical outcome. MYCN proteins target proliferation and apoptotic pathways, and have an important role in the progression of neuroblastoma. Here, we show that both wild-type and gain-of-function mutants in ALK are able to stimulate transcription at the MYCN promoter and initiate mRNA transcription of the MYCN gene in both neuronal and neuroblastoma cell lines. Further, this stimulation of MYCN gene transcription and de novo MYCN protein expression is abrogated by specific ALK inhibitors, such as crizotinib (PF-2341066), NVP-TAE684, and by small interfering RNA to ALK resulting in a decrease in proliferation rate. Finally, co-transfection of ALK gain-of-function mutations together with MYCN leads to an increase in transformation potential. Taken together, our results indicate that ALK signalling regulates initiation of transcription of the MYCN gene providing a possible explanation for the poor clinical outcome observed when MYCN is amplified together with activated ALK.Oncogene (2012) 31, 5193 --5200; doi:10.1038/onc.2012.12; published online 30 January 2012Keywords: neuroblastoma; anaplastic lymphoma kinase; ALK; MYCN; transcription factor INTRODUCTION Neuroblastoma is a neural crest-derived embryonal tumour of the postganglionic sympathetic nervous system and accounts for B15% of all deaths due to paediatric tumours. 1,2 Genetically, many cases of neuroblastoma show amplification of the MYCN gene (B24% of all cases), deletions of parts of the chromosomes 1p and 11q, gain of parts of 17q and triploidy. 1,3 --6 Anaplastic Lymphoma Kinase (ALK) Receptor Tyrosine Kinase (RTK) is mutated in both familial and somatic neuroblastoma. 7 --11 Moreover, these reports also indicated that downregulation or inhibition of ALK led to a marked decrease of cell proliferation, suggesting ALK as a critical factor in the initiation and progression of neuroblastoma. The ALK RTK was first described in the mid-nineties and aberrant ALK protein activity is now implicated in a range of nonhematopoietic, hematopoietic as well as neuroendocrine tumours (for a review see Palmer et al. 12 ). A recent meta-analysis of neuroblastoma has reported ALK gain-of-function mutations to be present at a frequency of 6.9% of investigated neuroblastoma tumours. Further, a comparison of the ALK mutation frequency in relation to genomic subtype revealed that ALK mutations were most frequently obs...

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Section: Resultsmentioning

confidence: 99%

Anaplastic Lymphoma Kinase (ALK) regulates initiation of transcription of MYCN in neuroblastoma cells

et al. 2012

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“…19 Since the PI3K/Akt signaling pathway and its downstream molecules are activated in neuroblastomas, 5,6,20 we have investigated the effects of inhibitors of this pathway in vitro and in vivo.…”

mentioning

confidence: 99%

“…[4][5][6] PI3K is a family of lipid kinases, heterodimeric proteins composed of one catalytic and one regulatory subunit. In the class IA PI3Ks, there are currently three isoforms of the catalytic (p110a, b, and d) and five of the regulatory (p50a, p55a, p85a, p85b, and p55c) subunits, where p50a and p55a are splice variants of p85a.…”

mentioning

confidence: 99%

Effects of small molecule inhibitors of PI3K/Akt/mTOR signaling on neuroblastoma growth in vitro and in vivo

Segerström

Baryawno

Sveinbjørnsson

et al. 2011

Intl Journal of Cancer

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Activation of the PI3K/Akt signaling pathway is correlated with poor prognosis in neuroblastoma, the most common and deadly extracranial tumor of childhood. In this study, we show that the small-molecule inhibitors of phosphoinositidedependent protein kinase-1 (PDK1) OSU03012 and the dual class I PI3K/mTOR inhibitor PI103 have profound effects on neuroblastoma survival in vitro and in vivo. Both OSU03012 and PI103 inhibited neuroblastoma growth in vitro. In treated cells, OSU03012 induced apoptosis and an S phase cell cycle arrest, whereas only minor apoptosis was detected in PI103 treated cells together with a G1 arrest. Both OSU03012 and PI103 downregulated phosphorylation of Akt and inhibited the downstream targets glycogen synthase kinase-3b (GSK3b) and p70 S6 kinase-1 (S6K1), as well as downregulated the expression of cyclin D1 and Mycn protein. Neuroblastoma cells expressing high levels of Mycn were more sensitive to OSU03012 or PI103 compared with cells expressing low Mycn levels. Both compounds significantly inhibited the growth of established, subcutaneous MYCN-amplified neuroblastoma xenografts in nude NMRI nu/nu mice. These results suggest that inhibition of the PI3K/Akt signaling pathway represent a clinical relevant target for the treatment of patients with high-risk MYCN-amplified neuroblastoma.Neuroblastomas are peripheral nervous system tumors that originate in the neural crest and are most commonly found in the adrenal medulla or along the sympathetic chain. 1 These tumors show heterogeneous biological and clinical features, in which a subset is prone to regress through spontaneous apoptosis with little or no therapy while another subset differentiates over time to benign ganglioneuromas. However, the majority of neuroblastomas are malignant with metastatic spread that is difficult to cure with current treatment modalities.2 Amplification of the MYCN gene, which occurs in 40-50% of the high-risk neuroblastoma cases, remains the major key predictor of poor outcome and is associated with advanced-stage disease, rapid tumor progression and low survival.3 Advanced-stage tumors and those with MYCN gene amplification typically show emergence of treatment resistance and new treatment alternatives for these patients are highly warranted.Abnormal activation of the PI3K/Akt signaling pathway is a common event in human cancers and has been validated through epidemiological and experimental studies as being essential for several human tumors, including neuroblastoma.4-6 PI3K is a family of lipid kinases, heterodimeric proteins composed of one catalytic and one regulatory subunit. In the class IA PI3Ks, there are currently three isoforms of the catalytic (p110a, b, and d) and five of the regulatory (p50a, p55a, p85a, p85b, and p55c) subunits, where p50a and p55a are splice variants of p85a. PI3Ks functions as signal transducers downstream of cell-surface receptors, such as receptor tyrosine kinases. Activated PI3Ks phosphorylate the lipid phosphatidyl-inositol 4,5-biphosphate (PIP2) to generate phosphatidyl-...

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“…Amplification of MYCN occurs in a large fraction of highrisk neuroblastoma and is associated with aggressive disease in children and poor clinical outcome [6]. Moreover, constitutive activation of phosphatidylinositol 3-kinase (PI3K)/ Akt as well as activation of Wnt signalling has recently been shown in primary neuroblastomas [22][23][24]. Activation of both these signalling pathways is associated with increased MYCN expression in neuroblastoma [22,24,25].…”

Section: Medulloblastoma and Neuroblastoma As Developmental Disordersmentioning

confidence: 99%

“…During the last years it has become increasingly clear that activation of PI3K/Akt signalling is an essential anti-apoptotic event and PI3K/Akt directly targets a number of pro-and anti-apoptotic proteins (reviewed in [109]). A majority of both medulloblastoma and neuroblastoma primary tumours constitutively express activated Akt [22,23,110], and inhibition of PI3K/Akt signalling induces apoptosis of neuroblastoma cells [22,25]. Moreover, activated Akt significantly augments Hedgehog-induced medulloblastoma in mice and activation of PI3K/Akt signalling is important for the proliferation of cancer stem cells residing in the perivascular niche following radiation of medulloblastoma [111].…”

Section: Signal Transduction and Apoptosis In Medulloblastoma And Neumentioning

confidence: 99%

Embryonal neural tumours and cell death

et al. 2009

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Medulloblastoma and neuroblastoma are malignant embryonal childhood tumours of the central and peripheral nervous systems, respectively, which often show poor clinical prognosis due to resistance to current chemotherapy. Both these tumours have deficient apoptotic machineries adopted from their respective progenitor cells. This review focuses on the specific background for tumour development, and highlights biological pathways that present potential targets for novel therapeutic approaches.

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Inhibitors of mammalian target of rapamycin downregulate MYCN protein expression and inhibit neuroblastoma growth in vitro and in vivo

Cited by 149 publications

References 37 publications

Anaplastic Lymphoma Kinase (ALK) regulates initiation of transcription of MYCN in neuroblastoma cells

Anaplastic Lymphoma Kinase (ALK) regulates initiation of transcription of MYCN in neuroblastoma cells

Effects of small molecule inhibitors of PI3K/Akt/mTOR signaling on neuroblastoma growth in vitro and in vivo

Embryonal neural tumours and cell death

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